Classical antiquity was a low point of human intelligence

Aristotle discussed adaptation by natural selection long before Darwin, yet despite his fame this theory remained ignored throughout antiquity. (Wikicommons)



Gabriel Andrade and Maria Campo Redondo have come out with a paper on the ancient Greeks and how they saw differences between human groups:

Critics of Rushton and Jensen, and of the very category of race, claim that race is a social construct that only came up in the 16th century, as a result of overseas voyages and the Atlantic slave trade. The goal of this article is to refute that particular claim, by documenting how, long before the 16th century, in classical antiquity race was already a meaningful concept, and how some Greek authors even developed ideas that bear some resemblance to Rushton and Jensen's theory. The article documents how ancient Egyptians already had keen awareness of race differences amongst various populations. Likewise, the article documents passages from the Hippocratic and Aristotelian corpus, which attests that already in antiquity, there was a conception that climatic differences had an influence on intelligence, and that these differences eventually become enshrined in fixed biological traits. (Andrade and Redondo 2019)

The ancients knew about psychological differences between human groups but usually put them down to the direct action of the climate. This environmental explanation seemed disproved by black Africans, or "Ethiopians" as they were called, because they and their descendants remained just as dark-skinned at northern latitudes. But this example of heritability didn't lead to a theory of genetics. Instead, black skin was seen as an indelible stain, perhaps due to divine punishment of Ham (or Cham), the ancestor of the Egyptians and black Africans, for seeing the nakedness of his father Noah (Goldenberg 2003). This view appears in a homily by the third-century Christian writer Origen: 

But Pharao easily reduced the Egyptian people to bondage to himself, nor is it written that he did this by force. For the Egyptians are prone to a degenerate life and quickly sink to every slavery of the vices. Look at the origin of the race and you will discover that their father Cham, who had laughed at his father's nakedness, deserved a judgment of this kind, that his son Chanaan should be a servant to his brothers, in which case the condition of bondage would prove the wickedness of his conduct. Not without merit, therefore, does the discolored posterity imitate the ignobility of the race.   Homily on Genesis XVI (Origen 2010)

In general, human differences were attributed to direct action by the environment:

Greek authors to a large extent believed that acquired characteristics were inherited. For example, the text On Airs, Waters and Places considers the people of Trapezus, who had the custom of artificially elongating their children's heads. The author of this text believed that this particular practice would make elongated heads in the future generations, without parents having to artificially do the procedure: "Thus, at first, usage operated, so that this constitution was the result of force: but, in the course of time, it was formed naturally; so that usage had nothing to do with it... If, then, children with bald heads are born to parents with bald heads; and children with blue eyes to parents who have blue eyes; and if the children of parents having distorted eyes squint also for the most part; and if the same may be said of other forms of the body, what is to prevent it from happening that a child with a long head should be produced by a parent having a long head?". Aristotle had similar ideas: "Mutilated young are born of mutilated parents".

Why wasn’t natural selection understood?

Ironically, and long before Darwin, the Greek philosopher Empedocles (494-434 BC) came up with another explanation: adaptation through natural selection. Change initially occurs by accident. If the change is good, the changed life-form will survive and reproduce; if not, it will perish. Good changes are therefore kept and bad changes lost. Thus, all aspects of living matter look "as if they were made for the sake of something," but this is only illusion. There is no conscious "maker" of all things. 

This idea was summarized by Aristotle (384-322 BC):

So what hinders the different parts (of the body) from having this merely accidental relation in nature? as the teeth, for example, grow by necessity, the front ones sharp, adapted for dividing, and the grinders flat, and serviceable for masticating the food; since they were not made for the sake of this, but it was the result of accident. And in like manner as to other parts in which there appears to exist an adaptation to an end. Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted by an internal spontaneity; and whatsoever things were not thus constituted, perished and still perish. Physicae Auscultationes 2:8, 2 (Darwin 1936 [1888], p. 3)

Aristotle's fame, as well as Empedocles', ensured that this idea would be read and passed on for generations, and yet it failed to take root in the minds of classical antiquity. It fell on barren ground. Aristotle himself rejected it, saying that all things must be for an end. Only much later, and independently, would natural selection be rediscovered.

The difficulty was not in understanding that humans, like other animals, are adapted to their environment. That part was obvious. The difficulty was in understanding adaptation as an indirect process. People more easily understood direct processes: something changed some people, and that change was passed on to their descendants. Aristotle himself fell for that idea when he mused that mutilated young are born to mutilated parents. 

This was the mentality of classical antiquity, and indeed of many people today. Change implies the existence of a changer, just as creation implies the existence of a creator. Few people rose above that level of thinking.


Did most people in classical antiquity think like children?

A Swiss psychologist, Jean Piaget (1896-1980), studied children in his country and concluded that all individuals go through stages of mental development. Children go through a "pre-operational stage" when causality is understood only in terms of conscious intent, specifically animism, artificialism, and transductive reasoning:

Animism is the belief that inanimate objects are capable of actions and have lifelike qualities. An example could be a child believing that the sidewalk was mad and made them fall down, or that the stars twinkle in the sky because they are happy. Artificialism refers to the belief that environmental characteristics can be attributed to human actions or interventions. For example, a child might say that it is windy outside because someone is blowing very hard, or the clouds are white because someone painted them that color. Finally, precausal thinking is categorized by transductive reasoning. Transductive reasoning is when a child fails to understand the true relationships between cause and effect. Unlike deductive or inductive reasoning (general to specific, or specific to general), transductive reasoning refers to when a child reasons from specific to specific, drawing a relationship between two separate events that are otherwise unrelated. For example, if a child hears the dog bark and then a balloon popped, the child would conclude that because the dog barked, the balloon popped. (Wikipedia 2019)

Piaget correctly observed Swiss children in the mid-20th century. He incorrectly concluded that the mind develops at the same pace in all humans (Oesterdiekhoff 2012). Indeed, you need not go far back to reach a time when most individuals never developed beyond the pre-operational stage. Just go back to classical antiquity.

At that time, the smart fraction was relatively small. Most intellectuals seemed to be loners. There were no academic societies, no academic journals, and no indications that large numbers of scholars did, or could, interact with each other. This point is made in an article on Roman science:

According to Sarton, who is the foremost living historian of science, "Roman science at its best was but a pale imitation of the Greek." "The Romans," he continues, "were so afraid of disinterested research that they discouraged any investigation the utilitarian value of which was not obvious."

Reymond remarked in his "History of Science" that the Romans were never distinguished for any love or even interest in pure science or abstract thinking. Virtually the same conclusion was reached by Heiberg, and Fowler made the interesting observation that even their literature and their philosophy had a practical object.

[...] historians of the economic life of ancient Rome have shown that there was a surprising paucity of inventions. They were not only few in number, but they lacked originality and were unimportant. (Salant 1938)

The Roman Empire was organizationally strong but intellectually weak. It depended on a store of knowledge that had been laid up in earlier times, notably by the ancient Greeks. This was the prevailing opinion among Roman writers, an opinion today dismissed as nostalgia for a mythical golden age.


The evidence of ancient DNA

"Cognitive archaeology" is a new field that has been made possible by retrieval of DNA from human remains and by calculation of polygenic cognitive scores from this DNA (based on alleles associated with educational attainment).

To date, two studies have used these research tools to chart changes in mean intelligence. The first study used ancient DNA from Europe and central Asia and found that the polygenic cognitive score gradually increased between 4,560 and 1,210 years ago (Woodley of Menie et al 2017).

This finding has been nuanced by a second study, using a sample of ancient DNA that was much larger and only from ancient Greece. It found that mean intelligence was initially high in ancient Greece and then began to decline after the end of the Mycenaean period in 1100 BC (Woodley of Menie et al. 2019). It looks like intelligence was at first strongly advantageous as humans adapted to increasing social complexity: farming, sedentism, literacy … Then something made it much less advantageous.

Mean intelligence was therefore lower during Roman times in comparison both to Greece in earlier periods and to Europe in later periods. 


Conclusion

So was Aristotle the Gregor Mendel of natural selection? Not really. Aristotle was much more famous than Mendel, and his works were read over a much longer span of time. Furthermore, Mendel's findings had to wait only 35 years before getting their due recognition. Aristotle's thoughts on natural selection lay dormant for more than two millennia before their significance was pointed out to Charles Darwin.

Aristotle didn't suffer from being insufficiently known. He had a worse handicap, especially in this case: not enough people could understand his line of reasoning. He was a lone voice in the wilderness over the many centuries separating him from Darwin. By Darwin’s time, many more people could understand natural selection, both in absolute numbers and as a proportion of the population. Even before The Origin of Species Darwin had a large audience of thinking people who could answer his questions and comment on his ideas. Earlier thinkers were not so lucky.

In the final analysis, the people of classical antiquity failed to understand natural selection for the same reason they failed to understand economics. They preferred to imagine cause and effect in simple terms: a person or personified thing producing a big change over a short time, and not impersonal forces producing an accumulation of small changes over a long time. They thought like children.


References

Andrade, G. and M.C. Redondo. 2019. Rushton and Jensen's Work Has Parallels with Some Concepts of Race Awareness in Ancient Greece. Psych 1 (1): 391-402.
https://www.mdpi.com/2624-8611/1/1/28/htm

Aristotle. Physics
http://classics.mit.edu/Aristotle/physics.2.ii.html

Darwin, C. (1936) [1888]. The Origin of Species and The Descent of Man. reprint of 2nd ed., The Modern Library, New York: Random House.

Goldenberg, D.M. (2003). The Curse of Ham. Race and Slavery in Early Judaism, Christianity, and Islam. Princeton: Princeton University Press.

Oesterdiekhoff, G.W. (2012). Was pre-modern man a child? The quintessence of the psychometric and developmental approaches. Intelligence 40: 470-478.
http://www.iapsych.com/iqmr/fe/LinkedDocuments/oesterdiekhoff2012.pdf

Origen (2010). Homilies on Genesis and Exodus, transl. by R.E. Heine., Washington D.C.: Catholic University of America Press
https://books.google.ca/books?id=X_mSBavPcq4C&pg=PA214&source=gbs_toc_r&cad=2#v=onepage&q&f=false 

Salant, W. (1938). Science and Society in Ancient Rome. The Scientific Monthly 47(6): 525-535.
https://www.jstor.org/stable/16625?seq=1#page_scan_tab_contents 

Woodley, M.A., S. Younuskunju, B. Balan, and D. Piffer. (2017). Holocene selection for variants associated with general cognitive ability: comparing ancient and modern genomes. Twin Res Hum Genet 20: 271-280.
https://www.cambridge.org/core/journals/twin-research-and-human-genetics/article/holocene-selection-for-variants-associated-with-general-cognitive-ability-comparing-ancient-and-modern-genomes/BF2A35F0D4F565757875287E59A1F534

Woodley of Menie, M.A., J. Delhez, M. Peñaherrera-Aguirre, and E.O.W. Kirkegaard. (2019). Cognitive archeogenetics of ancient and modern Greeks. London Conference on Intelligence 
https://www.youtube.com/watch?v=UES_tpDxz9A 

Wikipedia (2019). Piaget's theory of cognitive development. https://en.wikipedia.org/wiki/Piaget%27s_theory_of_cognitive_development#Concrete_operational_stage